This invention relates to a suction cap for the control of oil pressure regulation in an automatic gearbox, depending upon the suction or lowering in pressure created by the intake manifold of a motor, which suction is representative of the motor torque.
Embodiments of suction caps for the control of the pressure regulation in an automatic gearbox in relation to the motor suction are already known.
Some suction caps are equipped with a diaphragm. This diaphragm, on which the motor suction acts, works against a spring and makes it possible to change the position of the spool of the pressure regulating valve in a gearbox through a push-rod. This diaphragm also ensures the tightness between the gearbox which contains oil and that part of the cap which is connected with the motor suction.
Such a cap has many disadvantages. In particular, there is only one sealing means between the motor suction and the gearbox so that if the only diaphragm has a leak, the gearbox oil is rapidly sucked out by the motor because of the suction. Then the gearbox is most likely to be damaged owing to a lack of oil, and poor operation of the motor is possible because of gearbox oil getting into the fuel mixture.
A suction cap is also known which is equipped with a metallic bellows and a sealing bellows. This metallic bellows substantially performs the same function as the diaphragm in the above-mentioned example. The seal between the gearbox and the cap is obtained in this case by the sealing bellows.
This cap with a metallic bellows has the disadvantage of being bulky and expensive because the adjustment means of this cap is self-contained and distinct from the device which fastens it to the gearbox casing. This adjustment is indeed realized by a screw-nut device with a lock-nut and it is made by shifting the bearing cup of the cap spring in relation to the position of the push-rod given by the position of the required adjustment.
An object of this invention is to overcome the above-mentioned disadvantages.